Question

Problem 1 The force arm of a lever is 8 m long and the length of the load arm is 2 m. Calculate the force F needed to lift a 500 N load and find out the mechanical advantage of the lever.

Answer 1

The force needed to lift a 500 newton-load is 125 newtons.

The mechanical advantage of the lever is 4.

Step-by-step explanation:

Needed force is equal to the weight of the load. The Law of Lever, which is a particular case of the definition of Torque, states that force is inversely proportional to distance from fulcrum, that is:

`F_(F) \cdot r_(F) = F_(L)\cdot r_(L)` (1)

Where:

`F_(F)` - Needed force, in newtons.

`r_(F)` - Force arm, in meters.

`F_(L)` - Load force, in newtons.

`r_(L)` - Load arm. in meters.

The mechanical advantage of the lever (
`n`), no unit, is determined by following formula:

`n = (F_(F))/(F_(L))` (2)

If we know that
`F_(F) = 500\,N`,
`r_(F) = 2\,m` and
`r_(L) = 8\,m`, then the load force needed to lift is:

`F_(L) = F_(F) \cdot \left((r_(F))/(r_(L)) \right)`

`F_(L) = 125\,N`

The force needed to lift a 500 newton-load is 125 newtons.

And the mechanical advantage of the lever is:

`n = 4`

The mechanical advantage of the lever is 4.